Various types of conveyors have been utilized for conveying objects in industrial production lines. Objects may be conveyed from work station to work station individually or in groupings, depending on the object and the task to be performed. It may or may not be important to maintain any spacing or control of the objects during some or all of the travel. For example, apples being conveyed may simply be stacked randomly on a conveyor, while bottles being filled may be held rigidly in place by a filling machine that has received the bottles from a conveyor.
Certain conveyor belts (sometimes also called chains) are made of a plurality of interconnected links, driven by motors that engage the conveyor belt. Such conveying systems are commonly employed in the transportation of manufactured goods and articles, and for containers. With these typical systems, the motor drives a toothed drive sprocket that engages complimenting driving recesses or “dogs” formed on the conveyor belt. These drive units can be disposed in any number along the length of the conveyor belt. Such a drive unit and conveyor system is disclosed in U.S. Pat. No. 6,119,848 which is assigned to the assignee of the present invention, and is incorporated herein by reference in its entirety for all purposes.
Link type conveyor belts are sometimes designed having a knuckle/socket joint arrangement wherein one part of the link has a rounded knuckle and the opposite part has a socket formed by two extending edges. The knuckle of one link fits into the socket of a neighboring link. The knuckle is able to move in various directions within the socket, which allows for the conveyor system as a whole to curve and move.
The interconnected links typically have a platform member connected to or formed integral with the link's upper (conveying) surface. The platform member is generally shaped to match the neighboring platform members on other links such that the links can turn in a plane or twist while moving around curved sections of the conveying system, yet are also shaped such that the cracks and spaces formed between the links are minimized. The platform members can be connected to the links in several different ways. For instance, the platforms may have pegs extending therefrom which match corresponding slots on the links. Alternatively or additionally, the platforms can have snap springs which lock into place on corresponding sections of the links. Such a knuckle link with a platform surface member is disclosed in U.S. Pat. No. 6,209,716 which is owned by the assignee of the present invention and incorporated herein by reference in its entirety for all purposes.
Often times, it is the case that objects move or shift locations on the conveyor belt during transportation. This can be due to vibrations in the operation of the conveying system, centrifugal or tangential forces on the object when the conveying belt enters a curved section, or from simply being hit by other objects placed onto the conveyor belt. One way to prevent objects from moving on the surface of a conveyor belt is to apply a high friction surface element which keeps the objects in place. Such a technique is taught in U.S. Pat. No. 4,925,013 which is incorporated herein by reference in its entirety for all purposes.
Although the application of a friction surface element will minimize the aforementioned problems associated with the transport of goods, it may also create side-effect problems. For instance, an object placed on a high friction surface element will not move to a desired spot on the conveyor belt unless some other mechanical force is provided in which to move the object. Often times it is desired to specifically locate an object on a conveyor belt, and this cannot be accomplished if the object on a high friction surface is not initially placed in the desired location.
Further, it can also be the case in a particular application that a frictional or a high frictional surface is disfavored. This would be true if heavy objects were to be removed from the conveyor belt by use of a bar or other means to slide the objects off the belt. Having a heavy object on a high friction surface would necessitate the need to generate increased amounts of force to move the object from the conveyor belt, or would at least impede movement of the object from the belt. Additionally, it could be the case that a particular application requires the object to be positioned at a particular location on the conveyor belt surface. Having a frictional surface would again prevent or impede the movement of the object from one location on the surface platform of the conveyor belt to another.
Another problem associated with some conveyor systems is vibration which causes objects to be rotated from one orientation to another. Ways used in the prior art to prevent this include adding guide rails to either side of the conveyor track to keep the object in place. These guide rails are stationary with respect to the moving conveyor track. Although effective, this solution can be impractical in certain parts of the conveying system in which spatial constraints do not allow for the installation of guide rails.
One solution for securely conveying objects is a conveyor system where the conveying surface is sloped and a fixed rail is provided at the bottom of the slope on the platform member, as is disclosed in U.S. Pat. No. 6,601,697, which is owned by the assignee of the present invention and incorporated herein by reference in its entirety for all purposes. This arrangement works well to hold certain types of conveyed objects in a given position for its intended applications, but the fixed rail and slope could inherently prevent loading or unloading the conveyor in certain orientations. Thus, additional machinery could be required to load and/or unload the conveyor. Further, the conveyor platform members are configured in a given size, so the ability to use the conveyor for different sized containers may require using a different sized platform member.
U.S. patent application Ser. Nos. 10/712,405, 10/712,406, and 10/712,407, all filed Nov. 13, 2003, all describe and claim various different conveyor and link designs wherein conveyed objects such as containers may be gripped by the conveyors. The present application describes and claims certain variations and improvements in such gripping conveyors and links.